Why do diabetics get weak and their eye sight starts to fade?

Weakness in diabetics could be either from high blood sugar (hyperglycemia) or low blood sugar (hypoglycemia). Everyone doesn't respond the same to fluctuations in the blood glucose level.

Diabetes mellitus affects every organ system, the eyes are no exception. When blood glucose concentrations are high, the neurons (nerves) in the body are being deprived of the glucose they need to function normally. Over time, the nerves that connect to the eyes (and every where else) sustain damage( diabetic neuropathy) . This is why failing eyesight and even blindness in diabetics is so common.

Diabetes is the leading cause of blindness in the United States for individuals aged 20-74. Diabetes can effect vision in a number of ways but vision loss usually occurs due to two problems: proliferative diabetic retinopathy and macular edema. Both conditions can be treated with laser surgery if caught early.

Diabetics can actually have fluctuations in their vision abilities due to ups and downs in their blood sugar. As blood sugar changes in the body, the shape of the human crystalline lens changes.

Macular edema is the swelling of the macular tissue in the middle of the retina. It causes a lack of visual acuity.

Proliferative Diabetic retinopathy has the ability to actually damage the small blood vessels in the eye leading to profound vision loss. Damaging the vessels causes the retina to release chemicals which tell the body to create more blood vessels in the eye. These blood vessels break and bleed leading to scar tissue. As the scar tissue contracts it pulls on the retina causing detachment.

If you are looking at the eye question, the actual part of diabetes that causes the eyesight to weaken or fail is the overabundance of glucose in the blood. As this blood travels through the vessels of the eye, the heavy glucose content actually begins to weaken many of the very small blood vessels in the eye and the capillaries develop weak spots. Once the vessels become damaged enough, blood flow is actually closed off and the vessels die and are not replaced. In the worst cases, the bleeding and damage can actually lead to the retina coming loose from the eye.

This may have something to do with diabetic neuropathy. There are many different diabetic neuropathies, which are nerve disorders that are caused by diabetes. Approximately 60-70% of people with diabetes develop some from of neuropathy over the course of their lives. The risk of developing nerve problems increases with age.

Autonomic neuropathy affects many parts of the body including the eyes, more specifically the pupils. It makes the pupils less responsive to light so when lights are turned on or off a person may have difficulty seeing. In addition, these people may not be able to drive at night. Focal neuropathy also affects the eye. Eyes are often unable to focus and double vision occurs. This type of neuropathy occurs mostly in older people with diabetes.

Some forms of neuropathy that lead to weakness are focal neuropathy, proximal neuropathy, and peripheral neuropathy. Peripheral neuropathy is the most common type of neuropathy. Symptoms include numbness and tingling in the arms and legs with symptoms usually getting worse at night. Weakness is also a common symptom.